Field of the Invention
This invention relates generally to devices and methods for treating lung disease.
Description of the Related Art
Lung diseases are a problem affecting several millions of people. Chronic obstructive pulmonary disease (COPD), for example, is a significant medical problem affecting 16 million people or about 6% of the U.S. population. Lung cancer, as another example, is among the most prevalent forms of cancer, and causes more than 150,000 deaths per year.
One of the prevalent forms of treating COPD is the use of lung volume reduction (LVR) techniques. One of the emerging methods of LVR involves the endoscopic introduction of prostheses or implants into pulmonary passageways. Such a method and prosthesis is described, for example, in U.S. patent application Ser. No. 11/682,986. The prosthesis will typically restrict air flow in the inhalation direction, causing the adjoining lung compartment to collapse over time. The prosthesis, also called an endobronchial valve (EBV), is intended to control airflow into a lung compartment and may consist of a one-way, silicone, duckbill valve attached to a metallic self-expanding retainer that is covered with a polymer membrane. The EBV is implanted in the target airway using a delivery catheter inserted through the working channel of a bronchoscope. Upon implantation, the EBV allows distal air to vent from the isolated lung compartment (typically a lobe or segment) during exhalation but does not allow refilling of this compartment during inhalation. With each respiratory cycle, the amount of air in the target lung compartment is reduced (pneumoreduction), allowing better functioning lung compartments to take over more of the work of breathing. This method has been suggested as an effective approach for treating lung compartments that are not subject to collateral ventilation.
To ensure a good fit of an EBV and to prevent EBV migration from the original location in the airway where it is implanted, it is necessary to select an appropriately sized EBV for the target airway. Therefore, it is imperative to place the EBV implant in an airway that has a diameter within the EBV size range and that has is long enough to accommodate the EBV. Catheter-based devices for vascular measurements are unsuitable or too complex for measuring lung passageway diameters for EBV implantation. U.S. Pat. No. 6,450,976, for example, discloses a device to be used as an attachment to a catheter for measuring length as well as vascular diameter. The device uses rotation of an outer barrel relative to an inner tubular member to effect measurement. Measurement is provided by radially movable elements that contact the vascular wall. U.S. Pat. No. 5,919,147 discloses a similar catheter-based device that uses radially moving arms that expand out of the end of a tube to measure the diameter of a vessel. Measurement is made via graduations located axially at the proximal end of the catheter. Contact between the radial arms and the vessel must be detected by the surgeon in both the above devices. One drawback of these devices is their complex construction and operation. Since each requires rotation in order to effectuate measurement, they require two handed operation. In addition, their suitability for use with a bronchoscope for the specific case of airway diameter measurement is not established.
Therefore, a need exists for a quick and convenient method and device for determining whether an airway is suitable for placement of an EBV or other implant for effective LVR and/or for selecting an appropriately sized EBV or other implant for use in a given airway. Ideally, such a method/device could be used to either approximate a diameter and/or length of a potential target airway or could be used to confirm or select a size of EBV that is appropriate for a given airway. At least some of these objectives will be met by the embodiments described herein.
In certain situations, for example when an airway is too big or too small for EBV placement, another method to assist the lung volume reduction may be desirable. Indeed, several existing methods exist for endobronchial lung volume reduction (ELVR), with and without the use of restriction devices. U.S. Patent Publication No. 2005/0061322, for example, discloses a method in which the airway is sealed after air in the lung compartment is aspirated using an occlusion catheter. U.S. Pat. No. 6,997,189 discloses a method of contracting the diseased lung tissue using anchoring elements attached to cords, which are pulled through a catheter. U.S. Patent Publication No. 2007/0221230 discloses an implant that is used to bend a portion of the airway to effect lung volume reduction. Other methods of treatment have been disclosed that involve completely sealing the airway. These include use of plug-forming substances such as swellable collagen or metal as disclosed in U.S. Pat. Nos. 6,287,290, 6,878,141, 6,709,401 and 7,186,259. Installation of plug devices or obturators is disclosed in U.S. Pat. No. 7,144,392 and U.S. Patent Publication No. 2007/005083. Further methods of sealing lung passageways include inducement of fibrosis in the bronchial tubes by introducing an irritant substance such as disclosed in U.S. Pat. No. 6,682,520, U.S. Patent Publication Nos. 2006/0130830 and 2006/0276807.
Despite the innovations in endoscopic lung volume reduction, further improvements and alternative methods and systems would still be desirable. The embodiments described herein seek to achieve at least some of the objectives described above.